E f i f k h t t diErfaringer fra kohortestudier

DSPAP´s 9. årsmøde

Magnus WickmanMagnus WickmanSachs’ Children’s Hospital p

Karolinska InstitutetSt kh lStockholm

Study design

• Cross sectional studies, recall bias reversed causation errorno cause relationships only associations- no cause relationships, only associations

• Cohort studies- hypothesis generating, - exposure data collected before onset of disease,- no problem with recall bias – exp data collected before onsetp p- nested case control study

• Case control studies• Case control studies- exposure data collected at time for onset of disease- recall bias

l ti f t l- selection of controls

• Intervention studies: cause relationship can be provenp p(but if the disease is multi factorial?)

Birth cohortsBirth cohorts

• Population basedPopulation based- prevalence, risk factors

• Enriched for heredity or selectedfor other exposures- risk factors, mechanisms,

To start a birth cohort

Inclusion of all womenin early pregnancy Small cohort of selected

i di id l t t dy p g yin a pre-defined area

during a certain

individuals to studymechanisms

(N<400)period of time (N>10,000) (N<400)

Data onnon-

responders

Biologicalmarkersp

Inclusionrate = select until> 75-70%

inclusionrate

< 70%inclusion

rate

rate = select untilyou have the

number neededdi taccording to power

calculations

To start a birth cohort

Large cohort (N>10,000) Small selected cohortg ( )Phenotyping

importantL f ll t ?

Cases and controlsHigh follow up rate

Low follow up rate?

Early markers of inflammationEarly markers of inflammation

Natural course of disease/prevalence

Risk factors Prevention Early markers of inflammationand onset of disease

Outcome needs to be commonG

Risk factors – PreventionEarly events – Prediction

Gene-environment interactionGenetics - Epigenetics Genetics - Epigenetics

To start a birth cohort of 10,000

75% of 75% of 75% of 75% of 75%

Eligible 10,000

Study base 7,500

1-2 years follow up 5,625

4 years 4,218

8 years 3 1638 years 3,163

12 years 2,372 <25%y ,

A large birth cohortPro:• G t t iti

Con:• When to start recruitment?• Great opportunities

• Biological markers collected before,during and after onset of disease

• When to start recruitment? • Long period before harvest

- difficult with fundingR h ti t b• Exposure data collected before

onset of disease• Always new research questions

• Research questions may not bevalid at the time for harvest

• What about sustainability withiny q• Collaboration possible

- pooling of data- replication

your group?• Loss at follow ups • Relative expensivereplication

• Genetic material available if DNAE/RNAis sampled and sampled correctly

• Publication in major journals

p

• Publication in major journals

Think twice before you start – tougher than toughest endurance sport

Birth cohorts within GA2LENStudy Start N

ECA 1992 3754ECA 1992 3754BAMSE 1994 4089DARC 1998 562 ECA BAMSE

MAS 1990 1314LISA 1997 3097GINI B 1996 3739

DARC

GINI-B 1996 3739KOALA 2000 2834PIAMA-NHS 1996 3291

MAS

KOALAGINI-B

PIAMA-NHS

PIAMA NHS 1996 3291CO.N.ER 2004 653GEPSII 2003 704 CO.N.ER

LISA

AMICS-BAMICS-Barcelona 1996 487AMICS-Menorca 1997 482

T t l 25006AMICS-M

GEPSII

Total 25006

Examples of risk factors studied in relation to development of allergy relation to development of allergy

related disease

• Furred petsu ed pets

• SHSE (second hand tobacco smoke exposure)• SHSE (second hand tobacco smoke exposure)

• Food nutritions Mediterranean diet• Food – nutritions – Mediterranean diet- Breast milk

early fish intake (omega 3 antio idant itamins/- early fish intake (omega-3, antioxidant vitamins/ minerals)

- Fruit and vegetables- Fruit and vegetables

Esben Eller, Allergy 2008, gy

Sensitization (to at least 1 aero-allergen) and sensitization allergic asthmasensitization, allergic asthma

Cat only vs. no pet ownership:

Sensitization Allergic Asthma

OR 1.09 (0.74-1.61) OR 0.87 (0.73-1.05)

Lödrup Carlsen K.C. and the GA2LEN WP birth cohort consortium, submitted

Effect of allergen exposure and sensitisation at<3 years on lung function at 7 years<3 years on lung function at 7 years

NS= not sens S/LE= sensitised and low exp S/HE= sensitised and high exposureNS= not sens S/LE= sensitised and low exp S/HE= sensitised and high exposure

Illi S et al, The Lancet 2006

Second hand tobacco smoke exposurep(asthma, eczema, sensitization, lung function)

• SHSE during pregnancy (foetal exposure)

• Early SHSE of the infanty

• No controversiesN Engl J Med 2010;363:1139-45.

No controversies

0.34

0.32

F/tE

0.30

tPEF

0.28

No P Occ 1-9 >10 A+P

Reduced tPTEF/tE <0.20 measured within the first week of life as well as maternaldaily smoking during pregnancy are significant risk factors (independent) for

Lodrup Carlssen KC et al ERJ 1997 Lødrup Carlsen KC et al, PAI 1999

daily smoking during pregnancy are significant risk factors (independent) fordeveloping persistent bronchial obstr within the first 2 years of life

Foetal SHSE and asthma up to 4oe a S S a d as a up oyears of age

- children exposed to both prenatal and postnatal excluded

6

children exposed to both prenatal and postnatal excluded

4

5

3

4

R, 9

5% C

I

1

2OR

0

1

T i t P i t tL t tTransient PersistentLate onset

Lannerö et al, Respiratory Research 2005

Foetal SHS exp, but not postnatal SHS exp and risk ofasthma according to definition in 6 European birth cohorts

Neuman Å, in manuscript

Effect of regular pre- and postnatalmaternal smoking at the age of 10maternal smoking at the age of 10

SensitisationUCI 26 7UCI 26.7 Wheezing

UCI 19.06

7

5

Sensitization

Wheezing

Wheezing

4Odds ratio

and 3

Sensitization2

a d95% CI

3

0

1

1 atopic parent 2 atopic parentsNo atopic parent0

Increased risk of specific sensitisation and pre- and postnatal

tobacco smoke exposuretobacco smoke exposure

At 3 f d ll• At age 3: food allergens

At age 4 (postnatal only):

Kulig M et al. Allergy 1999

• At age 4 (postnatal only):

sens birch (OR 2.90)( )

sens cat (OR 2.68)Lannerö et al., Thorax 2008

Plausible preventive mechanisms of certain nutrients

• Fatty acids – long chain polyunsaturatedMaturation of the foetal immunsystem: Proliferation and production of cytokines - elicit effectory p ycell functions. Fatty acid composition of immune cells - affects phagocytosis, T-cell signaling and antigenpresentation capability. Support epithelial barrier integrity and reduce IL-4 mediated permeability

• Anti-oxidantsAnti oxidantsReduce the neg effects of oxidative stress in the mucus membrane of the airways

• Human milk - fatty acids, anti-oxidants, prebiotics etcHM contains indigestible oligosaccharides, promote the growth mainly of bifidobacteria. Stimulates the development of the infant's own immune systemSecretory IgA antibodies directed towards the microbes in the mother's gut and her food proteinsSecretory IgA antibodies directed towards the microbes in the mother s gut and her food proteins. May enhance the infant's capacity to develop allergen tolerance

Maternalconsumption

Apples

1.61-4/ >4/ 1-4/ >4/ 1-4/ >4/ <1/ >1/ <1/ >1/

Total fish Oily fishconsumptionduringpregnancy

1.2

1.4 w w w w w w w w w w

OR, CI95% 0.8

1

0 4

0.6

0.2

0.4

Everwheeze

Doctorconfirmedasthma

Ever asthma

Doctorconfirmedeczema

Doctorconfirmedhay fever

0Outcome at5 years

asthma eczema hay fever

Willers S et al, Thorax on line 2007

OR and 95%CI per unit increase for fishti

1 6

1.8

consumption

1 2

1.4

1.6

0.8

1

1.2OR,

95%CI

0.4

0.6

0

0.2

E S ifi S ifi SPT t P i t t At iEczema

at1 year

SpecificIgE (mites,

grass) at4 years

SpecificIgE to

Hdm at4 years

SPT toHdm

at6 years

Persistentwheeze

at6 years

Atopicwheeze

at 6 yearsy y y y y y

Romieu I et al, Clin Exp All 2007

Fish consumption at age 1 and longitudinal development of allergic diseases up to 8 yrs (GEE) after adjustment, g p y ( ) j ,

N=3,265

842 1 yrsEczema

Overall effect

Asthma42 1 yrs

After excl*Overall effect

8 4

After excl*Overall effect

Rhinitis

8 4 21 yrs

35 65 1 2

After excl*Overall effect

* exclusion of children with early symptoms

.35 .65 1 2Odds ratio (95% CI)

Why does fish intake reduces the riskWhy does fish intake reduces the risk of onset of allergy related disease gyand supplementation of omega 3

fatty acid not?fatty acid not?

Breastfeeding - lots of controversies g(asthma, eczema, sensitisation)

• Possible preventive effective – duration is importantp

• Composition of human milk may vary

• In a population where the majority is breastfed for at least 3-4 months – effect of human milk on development of allergicof human milk on development of allergic disease is minor

4 months excl breastfeeding or more and asthma upt 8 f i 3400 hild GEE d lto 8 years of age in 3400 children – GEE model

2 yrs1 yr

Recurrent wheeze

8 yrs4 yrs

Overall effect 0-8 yrs

2 yrs1 yr

Overall effect after excl†

Asthma

8 yrs4 yrs2 yrs

Overall effect 0-8 yrsOverall effect after excl †

Overall effect 0 8 yrs

.35 .65 1 2

* ( % C )

Kull I et al, JACI 2010

Adjusted odds ratios* (95% CI)

Joint project BAMSE/Stockholm andJoint project BAMSE/Stockholm and CAPS/Sydney on breastfeeding and allergy

disease related outcomesdisease related outcomes

Di i N th E d A t li• Discrepancies Northern Europe and Australia• BAMSE – population based cohort• CAPS – selected cohort with intervention• Discrepancies are to 100% explained byDiscrepancies are to 100% explained by

difference in selection. When BAMSE is selected in the same manner effects less prevalentin the same manner effects less prevalent. Reversed causation can not be ruled out

Individual fruits and vegetables and allergic disease Cross-sectional analysis at age 8 years.

Highest vs. lowest quartile (OR and 95% CI)

Apples/pears

ALL CHILDREN

O i /l kAtopic sensitization

Eczema Asthma

Allergic rhinitisApples/pears

C tAtopic sensitization

Eczema Asthma

Allergic rhinitisOnions/leek

LAtopic sensitization

Eczema Asthma

Allergic rhinitis Carrots

Atopic sensitizationEczemaAsthma

Allergic rhinitis Legumes

.25 .5 1 1.5 2 2.5 3.5 4.5Odds ratio (95% CI)

Adjusted for sex, socioeconomic status, maternal smoking during pregnancy and/or at baseline, iso-BMI, maternal age at baseline, and parental history of allergic disease.

Rosenlund , JACI 2011

Individual fruits and vegetables andIndividual fruits and vegetables and allergic disease – after exclusion

Allergic rhinitisAples/pears

AFTER EXCLUSION

Allergic rhinitisOnions/leek

Atopic sensitization Eczema Asthma

Allergic rhinitis

CarrotsAtopic sensitization

Eczema Asthma

Allergic rhinitis

LegumesAtopic sensitization

Eczema Asthma

Allergic rhinitis

Atopic sensitization Eczema Asthma

Allergic rhinitis g

25 5 1 1 5 2 2 5 3 5 4 5.25 .5 1 1.5 2 2.5 3.5 4.5Odds ratio (95% CI)

Adjusted for sex, socioeconomic status, maternal smoking during pregnancy and/or at baseline, iso-BMI, maternal age at baseline, and parental history of allergic disease.

Rosenlund, JACI 2011

Utility of risk assessment data from birth cohorts

• Can be used in national guidelines on ti i l k d i t tiprevention since we lack good intervention

studies on the effect of:• SHSE• Pet keeping• Pet keeping• Maternal diet during pregnancy, lactation• Diet of the baby the first year of life

Development of allergy related diseases over time

Prevalence of allergic diseases in the BAMSEcohort shown as mean with 95%CIcohort shown as mean with 95%CI

25%Asthma

25% 25%Eczema All rhinitis

15

20

15

20

15

20

10 10 10

5 5 5

Age in years

01 2 4 8 12

01 2 4 8 12

01 2 4 8 12

Trends in eczema in the first 18 years of life: results fromthe Isle of Wight 1989 birth cohort study

Boys Girls

the Isle of Wight 1989 birth cohort study

18 6.4 8.34 3

5.5 8.99.4

144.3

50

6

10%55 46

6558 41

50

2

6 65

02

2 4 10 18 2 4 10 18Age in years

Ali Ziyab, Graham Roberts et al, Clin Exp 2010

Early co-morbidity and the allergic marchmarch

Infant wheeze and outcome of any allergy related disease at 8 years of age N=3279disease at 8 years of age, N=3279

Infants with wheeze, N= 830 (25 %)

Between 1and 2 years

Non infant wheezers, N=2449 (75 %)N= 830 (25 %)and 2 years N=2449 (75 %)

Allergic diseaseamong early wheezers

N=312/817Complete

i i

Allergic disease amongnon early wheezers

N=598/2391N=312/817(38%)

remissionN=505/817

(62%)Ec ema

(25%)

EczemaN=181/812

(22%)

EczemaN=413/2396

(17%)

RhinitisAsthmaRhinitis

N=156/828(19%)

AsthmaN=116/824

(14%)

At 8 years RhinitisN=288/2443

(12%)

AsthmaN=91/2436

(4%)

Åsa Neuman,in manuscript

Prognostic value of IgE sensitization in some of the GA2LEN Birth Cohorts

Prevalence of asthma, wheeze up to age 7and increased BHR in relation to age atand increased BHR in relation to age at onset of allergic sensitisation over time

No sensitisation, n=342, 54%Transient sensitisation (0-2 yrs), n=82, 13%

s

50

**Late sensitisation, n=117, 18%Persistent sensitisation, n=99, 15%

t age

7 y

ears

40

30**

**ence

in %

at 30

20**

**

**

Pre

vale

10

5 *

Any of cow’s milk egg white soy bean wheat dust mite cat dog grass mix birch >0 35 kU/l

Asthma ever Current wheeze0

Current asthma Current BHR

Any of cow s milk, egg white, soy bean, wheat, dust mite, cat, dog, grass mix, birch, >0.35 kU/l

Sabina Illi et al, JACI 2001 and 2004

The prevalence of allergic diseases and sensitization in 6-year-old childrensensitization in 6 year old childrenFollow-up of the DARC birth cohort

Kjaer HF et al PAI 2009

The prevalence of allergic diseases and sensitization in 6-year-old childrensensitization in 6 year old childrenFollow-up of the DARC birth cohort

Kjaer HF et al PAI 2009

Early sensitisation is a risk factor forEarly sensitisation is a risk factor for allergy related disease later in childhood

i tor even in teenage

Screen for atopic constitution early when symptoms of moderate or severesymptoms of moderate or severe eczema or wheeze in particular if

parental allergy

Clinical interpretation of s-IgE levels

1.0s FoodsInhalant allergens

0.8

s/sy

mpt

oms FoodsInhalant allergens

0.6

fic d

iagn

osis

0.4

rgen

-spe

cif

0.2

bilit

y of

alle

r

00.35 0.7 3.5 17.5 50 100

Pro

bab

IgE antibody concentration (kUA/L)

Sensitisation and probability of symptoms to the same food at 4 years, N=2,614

n=195* n=111* n=17

80

100n 195

s to

milk

(%)

n 111

80

100

s to

egg

(%)

80

100n 17

ms

to fi

sh (%

)

Milk Egg Fish

40

60

lity

of s

ympt

oms

40

60

ity o

f sym

ptom

s

40

60

ility

of s

ympt

om

0.35 1 3 10 30 100

0

20

Pro

babi

l

0.35 1 3 10 30 1000

20

Pro

babi

l

0

20

0.35 1 3 10 30 100

Pro

bab

IgE ab levels (kUA/L) IgE ab levels (kUA/L) IgE ab levels (kUA/L)

100n=88

at (%

)

ean

(%)n=112*

100

ut (%

)

Peanut100

n= 68*

Soy Wheat

60

80

mpt

oms

to w

hea

ptom

s to

soy

be

60

80

mpt

oms

to p

eanu Peanut

60

80

OR=1.8CI 95% 0.9-3.3

Soy Wheat

20

40

roba

bilit

y of

sym

obab

ility

of s

ym

20

40

roba

bilit

y of

sym

20

40

Östblom E, Allergy 2008

0.35 1 3 10 30 100IgE ab levels (kUA/L)

0PrPro

IgE ab levels (kUA/L) 0.35 1 3 10 30 100

0Pr

IgE ab levels (kUA/L) 0.35 1 3 10 30 100

0

Proportion of children who reacts to peanuts among thosesensitised to peanuts only or to peanuts and birch among 8

year olds (N=2,405)

100

90

100

80ms

to Ara h 2

60

70

h sy

mpt

omut

(%

) Ara h 8 but also some with

Ara h 2

40

50

rtio

n w

ithpe

anu Ara h 2

10

20

30

Prop

o

0

10

Peanut, but notbirch

Peanut, butalso birch

Allergen spec IgE >0.35 kU/L

birchalso birch

Comparison between studies of probability of symptomsto peanut in relation to increased levels of peanut

specific IgE antibodies

11

0.8

0.9ab

ility

0.7

0.6

0 5

Pro

ba

0.3

0.4

0.5

0.2

0.1

00.35 3 3010 1001

0

A j BAMSE 8 t t bi h

Prospective Sampson H Retrospective Sampson H

Asarnoj, BAMSE 8 yrs, peanut and birchAsarnoj, BAMSE 8 yrs, peanut, not birch

Sens peanutnot birch

74% 43% 8% 0%

Sens peanutand birch

Sens birch,not peanut

No sens Peanut, no birch Semi-quantitative

micro array

ms

pean

ut

ms

pean

ut

ms

pean

ut

ms

pean

utN=50 N=50 N=50 N=50 techniqueA

ra h

1A

ra h

2A

ra h

3

Ara

h 8

Bet

v 1

Sym

ptom

Ara

h 1

Ara

h 2

Ara

h 3

Ara

h 8

Bet

v 1

Sym

ptom

Ara

h 1

Ara

h 2

Ara

h 3

Ara

h 8

Bet

v 1

Sym

ptom

Ara

h 1

Ara

h 2

Ara

h 3

Ara

h 8

Bet

v 1

Sym

ptom

Ara h 2 and 1 and 397% report reaction

If ll th 50%If all three: 50% report lower

respiratory reactions

If only Ara h 8 = 15%

Asarnoj A et al.Allergy 2010

Q tit ti I E d l i fQuantitative IgE and analysis of allergen components are useful g p

diagnostic tool to better understand underlying allergic diseaseunderlying allergic disease

Large national cohorts in Scandinavia –future in birth cohort research?

• The Nordic countries are well suited for this kind of research• The Nordic countries are well suited for this kind of research because of their population-based registers on diseases, demography and social conditions, linkable at the individual level by means of the unique ID-number given to all citizens. q g

• The Danish National Birth Cohort1996-199960 000 t60 000 pregnant women

• The Norwegian Mother and Child Cohort Study 1999 20081999-2008100 000 newborns

• LifeGene SwedenLifeGene, SwedenPilot 2009, Aim: 500 000 individuals all agesBorn into a cohort recruited through women 18-45 years

Next generation of “birth” cohort studies:Next generation of “birth” cohort studies:

• Time window – recruitment early in b fpregnancy or even before

• Better characterisation of phenotypes

• Better characterisation of environment to study interactionsy

• Gene – environment interaction studies• Gene environment interaction studies